Breast Cancer Risk Factors
Everyone wants to know what they can do to lower their breast cancer risk. Although doctors don’t know what causes breast cancer, they do know there are factors linked to a higher-than-average risk of developing the disease. Some factors associated with an increase in breast cancer risk — being a woman, your age, and your genetics, for example — can't be changed. Other factors — lack of exercise, smoking cigarettes, and eating certain foods — can be altered by making lifestyle choices.
By choosing the healthiest lifestyle options possible, you can empower yourself and make sure your breast cancer risk is as low as possible.
The known risk factors for breast cancer are listed below. Click on each link to learn more about the risk factor and ways you can minimize it in your own life. If a factor can't be changed (such as your genetics), you can learn about protective steps to help keep your risk as low as possible.
Known breast cancer risk factors
Sex: Being a woman, or a person assigned female at birth, is one of the most important risk factors for developing breast cancer.
Age: As with many other diseases, your risk of breast cancer goes up as you get older. About two out of three invasive breast cancers are found in women 55 or older.
Family History: Women with close relatives — especially sisters, mothers, or daughters — who have been diagnosed with breast cancer have a higher risk of developing the disease.
Genetics: About 5% to 10% of breast cancers are thought to be hereditary, caused by abnormal genes passed from parent to child.
Personal History of Breast Cancer: If you've been diagnosed with breast cancer, you're three to four times more likely to develop a new cancer in the other breast or a different part of the same breast.
Radiation to Chest or Face Before Age 30: If you had radiation to the chest or face to treat another cancer or acne, you have a higher-than-average risk of breast cancer.
Certain Breast Changes: If you've been diagnosed with certain benign (not cancer) breast conditions, you may have a higher risk of breast cancer.
Race/Ethnicity: White women are slightly more likely to develop breast cancer than Black, Hispanic, and Asian women. But Black women are more likely to develop more aggressive, more advanced-stage breast cancer diagnosed at a young age.
Being Overweight: Overweight and obese women have a higher risk of being diagnosed with breast cancer compared to women who maintain a healthy weight, especially after menopause.
Pregnancy History: Your age when you give birth to your first child and the number of times you’ve given birth — including if you’ve never had a full-term pregnancy — can affect your risk of developing breast cancer.
Breastfeeding History: Breastfeeding can lower breast cancer risk, especially if you breastfeed for longer than one year.
Menstrual History: Women who had their first period before they turned 12 have a higher risk of breast cancer later in life.
Using HRT (Hormone Replacement Therapy): Some types of HRT can increase the risk of breast cancer in people with certain risk factors.
Drinking Alcohol: Research shows that drinking alcoholic beverages of any kind increases a woman's risk of hormone receptor-positive breast cancer.
Dense Breasts: Women with dense breasts have a higher risk of developing breast cancer.
Lack of Exercise: Research shows a link between exercising regularly at a moderate or intense level for four to seven hours per week and a lower risk of breast cancer.
Smoking: Smoking is linked to a higher risk of breast cancer in younger, pre-menopausal women.
Emerging breast cancer risk factors
Low Vitamin D Levels: Research suggests that women with low levels of vitamin D have a higher risk of breast cancer.
Light Exposure at Night: The results of several studies suggest that women who work at night — so they’re exposed to bright light when their bodies want to sleep — have a higher risk of breast cancer compared to women who work during the day.
DES (Diethylstilbestrol) Exposure: Women who were exposed to DES while their mothers were pregnant with them may have a slightly higher risk of breast cancer later in life.
Eating Unhealthy Food: Diet is thought to be at least partly responsible for about 30% to 40% of all cancers.
Exposure to Chemicals in Hair Dyes and Straighteners: Some studies suggest that there could be a link between exposure to hair dyes and straighteners and the development of breast cancer.
Exposure to Chemicals in Cosmetics: Research strongly suggests that at certain exposure levels, some of the chemicals in cosmetics, including triclosan, may contribute to the development of cancer in people.
Exposure to Chemicals in Food: Between pesticides, antibiotics, and mercury, there are concerns that exposure to chemicals in food products may cause an increased risk of breast cancer.
Exposure to Chemicals for Lawns and Gardens: Research strongly suggests that at certain exposure levels, some of the chemicals in lawn and garden products may cause cancer.
Exposure to Chemicals in Plastic: Research strongly suggests that at certain exposure levels, some of the chemicals in plastic products, such as bisphenol A (BPA), may cause cancer.
Exposure to Chemicals in Sunscreen: There are some concerns about specific chemicals sometimes found in sunscreen products being linked to cancer.
Exposure to Chemicals in Water: Some drinking water, whether from a tap or a bottle, may be contaminated with chemicals or substances linked to cancer.
Exposure to Chemicals When Food Is Grilled or Prepared: Research has shown that women who ate a lot of grilled, barbecued, and/or smoked meats may be at increased risk of breast cancer.
Exposure to High Levels of Fine-Particle Air Pollution: Research suggests that women who live and work in places with high levels of fine-particle air pollution, such as dust, dirt and smoke, have a higher risk of breast cancer.
Fears with no evidence
Some factors have been widely rumored to increase breast cancer risk, but there is no conclusive evidence behind these claims.
Abortion: Research shows abortion is not linked to an increased risk of breast cancer.
Antiperspirants: Research to date has not found a link between use of antiperspirants and breast cancer.
Bras: There's no evidence that wearing a bra increases the chance of developing breast cancer.
Dairy: The current research doesn't show any links between dairy and breast cancer. Some dairy products may actually lower breast cancer risk.
— Last updated on September 9, 2025 at 2:27 PM
